Questions

Humming bird is the smallest bird and the only bird which can fly in backwards in the world.

The Lamprey fish is characterized by an absence of jaws.

Fragmentation occurs in a dynamic memory allocation system when many of the free blocks are too small to satisfy any request.

The kilowatt hour (kW⋅h) is a composite unit of energy equivalent to one kilowatt (1 kW) of power sustained for one hour.

One watt is equal to 1 J/s. One kilowatt hour is 3.6 megajoules.

Sound waves cannot be transmitted through vacuum. 

Proxima Centauri is the nearest star to the Earth.

The oxygenated blood  flows through pulmonary veins then leaves the lungs, which return it to the left heart, completing the pulmonary cycle.